Discrimination of Rock Units in Karst Terrains Using Sentinel-2A Imagery

We explored the potential incorporation of Sentinel-2A imagery for rock unit determination in the Croatian karst region dominated by carbonate rocks. The various lithological units are potential sources of both stone aggregates and dimension stone, and their spatial distribution is of high importance for mineral resource management. The presented approach included the preprocessing and processing of existing analog data (geological maps), Sentinel-2A satellite images and the United States Geological Survey spectral indices, all in combination with ground truth data. Geological mapping and digital processing of legacy maps using the K-means and random forest algorithm reduced the spatial error of the geometry of geological boundaries from 100 m and 300 m to below 100 m. The possibility of discriminating individual lithological units based on spectral analysis and discriminant function analysis was also examined, providing a tool for evaluating the geological potential for mineral resources. Despite the challenges posed by the lithological homogeneity of karst terrain, the results of this study show that the use of spectral signature data derived from Sentinel-2A satellite images can be successfully implemented in such terrains for the enhancement of existing geological maps and mineral resources exploration

Discrimination of Rock Units in Karst Terrains Using Sentinel-2A Imagery

We explored the potential incorporation of Sentinel-2A imagery for rock unit determination in the Croatian karst region dominated by carbonate rocks. The various lithological units are potential sources of both stone aggregates and dimension stone, and their spatial distribution is of high importance for mineral resource management. The presented approach included the preprocessing and processing of existing analog data (geological maps), Sentinel-2A satellite images and the United States Geological Survey spectral indices, all in combination with ground truth data. Geological mapping and digital processing of legacy maps using the K-means and random forest algorithm reduced the spatial error of the geometry of geological boundaries from 100 m and 300 m to below 100 m. The possibility of discriminating individual lithological units based on spectral analysis and discriminant function analysis was also examined, providing a tool for evaluating the geological potential for mineral resources. Despite the challenges posed by the lithological homogeneity of karst terrain, the results of this study show that the use of spectral signature data derived from Sentinel-2A satellite images can be successfully implemented in such terrains for the enhancement of existing geological maps and mineral resources exploration

Rare Earth Elements Enrichment in the Upper Eocene Tošići-Dujići Bauxite Deposit, Croatia, and Relation to REE Mineralogy, Parent Material and Weathering Pattern

Tošići-Dujići bauxite deposit, situated in Dalmatian inlands, Croatia, contains minor remaining bauxite reserves. The deposit lies on Lower Eocene foraminiferal limestone and is covered by Upper Eocene Promina sediments. Bauxite samples were analyzed for textural, mineralogical, and geochemical features in order to determine absolute REE abundances and their relation to mineralogy, as well as to devise the origin of REE enrichment and to trace weathering and bauxitization paths of the parent material. The samples show total REE abundances up to 3500 mg/kg with significant HREE enrichment in some cases. All samples are gibbsitic with hematite and anatase as major phases. Kaolinite occurs in most of the samples, and goethite, böhmite, and nordstrandite are minor phases. Monazite-(Ce) and xenotime-(Y) were identified as detrital REE minerals as well as authigenic florencite-(Ce). In the REE most abundant sample, REE are most likely bound to Fe- and Ti-oxide phases as suggested by correlation analysis. Chemical weathering proxies show intensive weathering. Geochemical and textural data imply that the REE enrichment is influenced by intensive weathering (CIA 97.87–99.26) of detrital material, and also by possible deposition/redeposition of residual material potentially derived and mobilized from various sedimentary rocks of the area

Rare Earth Elements Enrichment in the Upper Eocene Tošići-Dujići Bauxite Deposit, Croatia, and Relation to REE Mineralogy, Parent Material and Weathering Pattern

Tošići-Dujići bauxite deposit, situated in Dalmatian inlands, Croatia, contains minor remaining bauxite reserves. The deposit lies on Lower Eocene foraminiferal limestone and is covered by Upper Eocene Promina sediments. Bauxite samples were analyzed for textural, mineralogical, and geochemical features in order to determine absolute REE abundances and their relation to mineralogy, as well as to devise the origin of REE enrichment and to trace weathering and bauxitization paths of the parent material. The samples show total REE abundances up to 3500 mg/kg with significant HREE enrichment in some cases. All samples are gibbsitic with hematite and anatase as major phases. Kaolinite occurs in most of the samples, and goethite, böhmite, and nordstrandite are minor phases. Monazite-(Ce) and xenotime-(Y) were identified as detrital REE minerals as well as authigenic florencite-(Ce). In the REE most abundant sample, REE are most likely bound to Fe- and Ti-oxide phases as suggested by correlation analysis. Chemical weathering proxies show intensive weathering. Geochemical and textural data imply that the REE enrichment is influenced by intensive weathering (CIA 97.87–99.26) of detrital material, and also by possible deposition/redeposition of residual material potentially derived and mobilized from various sedimentary rocks of the area

Kritične mineralne sirovine – europski i svjetski tokovi sirovina u službi ubrzanog tehnološkog razvoja

Suvremeni razvoj raznih grana proizvodne djelatnosti kao i napredak tehnologije zahtijevaju odgovarajuću opskrbu mineralnim sirovinama. Pojedine sirovine posebno su tražene u proizvodnji i razvoju novih proizvoda, a njihova ograničena opskrba ili čak prekid dobave mogu ozbiljno ugroziti proizvodnju i daljnji razvoj, ugroziti sigurnost radnih mjesta te poljuljati lokalno gospodarstvo. Stoga je zadovoljavajuća i pravovremena opskrba ključnim sirovinama nužan preduvjet svakodnevnog funkcioniranja suvremenih gospodarskih tokova, a time i bitna odrednica strateškog planiranja svake države. Nedovoljna dostatnost pojedine sirovine na tržištu može biti posljedica nedostatne domaće proizvodnje i ovisnosti o uvozu s udaljenih tržišta, ali i prekida opskrbe uslijed ekonomskih, prirodnih i geopolitičkih faktora. Ti čimbenici također utječu na čestu fluktuaciju cijena sirovine, koja se dalje odražava na planiranje proizvodnje, cijenu konačnog proizvoda, kao i na poremećaje u proizvodnji ako volatilnost cijena ugrožava zacrtane proizvodne i razvojne ciljeve, a svakako može utjecati i na smanjenje konkurentnosti pojedinih industrija na tržištu. Sirovine nužne za proizvodnju, a nedostatne na domaćem tržištu, podložne čestim promjenama u dostupnosti i cijeni te povećanog rizika u opskrbi, smatraju se kritičnim sirovinama (European Commission Communication, 2011). Često se kod ove problematike naizmjence koristi izraz „kritične sirovine“ i „kritične mineralne sirovine“, budući da mineralne sirovine svojom brojnošću i obujmom proizvodnje čine najveći dio kritičnih sirovina

Kritične mineralne sirovine – europski i svjetski tokovi sirovina u službi ubrzanog tehnološkog razvoja

Suvremeni razvoj raznih grana proizvodne djelatnosti kao i napredak tehnologije zahtijevaju odgovarajuću opskrbu mineralnim sirovinama. Pojedine sirovine posebno su tražene u proizvodnji i razvoju novih proizvoda, a njihova ograničena opskrba ili čak prekid dobave mogu ozbiljno ugroziti proizvodnju i daljnji razvoj, ugroziti sigurnost radnih mjesta te poljuljati lokalno gospodarstvo. Stoga je zadovoljavajuća i pravovremena opskrba ključnim sirovinama nužan preduvjet svakodnevnog funkcioniranja suvremenih gospodarskih tokova, a time i bitna odrednica strateškog planiranja svake države. Nedovoljna dostatnost pojedine sirovine na tržištu može biti posljedica nedostatne domaće proizvodnje i ovisnosti o uvozu s udaljenih tržišta, ali i prekida opskrbe uslijed ekonomskih, prirodnih i geopolitičkih faktora. Ti čimbenici također utječu na čestu fluktuaciju cijena sirovine, koja se dalje odražava na planiranje proizvodnje, cijenu konačnog proizvoda, kao i na poremećaje u proizvodnji ako volatilnost cijena ugrožava zacrtane proizvodne i razvojne ciljeve, a svakako može utjecati i na smanjenje konkurentnosti pojedinih industrija na tržištu. Sirovine nužne za proizvodnju, a nedostatne na domaćem tržištu, podložne čestim promjenama u dostupnosti i cijeni te povećanog rizika u opskrbi, smatraju se kritičnim sirovinama (European Commission Communication, 2011). Često se kod ove problematike naizmjence koristi izraz „kritične sirovine“ i „kritične mineralne sirovine“, budući da mineralne sirovine svojom brojnošću i obujmom proizvodnje čine najveći dio kritičnih sirovina